[Editors note: Back in February 2010, Fast Company was wowed by a neat little iPhone app called Siri. "As you can see, using Siri is a lot like talking to a really, really well-informed friend," Dan Macsai wrote in a post, which we've dug up here. In April 2010, Apple bought Siri. Today, Tim Cook reintroduced Siri as a primary addition to iOS 5. Turns out what wowed us then is what wowed Apple watchers today, too.]

For decades, companies have tried to create the real-life equivalent of Rosie the Robot-Maid, an electronic personal
assistant that actually works, and is actually personal. It's a task easier said than done: Just ask Apple, whose "handwriting recognition" Newton handhelds were discontinued in the '90s, or Chandler, whose note-to-self Web organizer has been in development since 2001, and now seems outdated. But with mobile Internet use at an
all-time high—and smartphone tech smarter than ever—the market is ripe for a legitimate successor. And its name is Siri.

Siri, which launches today as a free iPhone app, is a virtual personal assistant that amazingly resembles...an actual personal assistant. It understands plain English commands, which can be spoken or typed (e.g., "Get me tickets to that Matt Damon movie"). It remembers personal details, so you never have to tell it more than once where, for example, "my office," "my apartment," and "my girlfriend's house" are. And once you've stored your credit card information, it can transact on your behalf—with your expressed consent, of course. Here's a demo:

As you can see, using Siri is a lot like talking to a really, really well-informed friend. By plugging into APIs from more than 30 different partners, including Yelp, Eventful, and Fandango, the app can discern great date spots, tell you what's going on in your neighborhood, and even call you a cab if you spout something nonsensical, like "take me drunk I'm home." It also remembers your specific account credentials, so you can get your OpenTable points or use your MovieWatcher card.

Oh, and if Siri doesn't understand your request? It'll either ask you to edit the text (perhaps you were mumbling?) or provide relevant search results from Bing. A free human assistant, by contrast, would probably just stare blankly and say "Huh?"

To be fair, there's a lot Siri still can't do: buy plane tickets, work on Blackberries/Android phones, properly respond to the phrase "What up?" (No, Siri, I wasn't talking about the Pixar movie!) But it's off to a pretty good start. And in the coming months, it will tweak its interface, release new smartphone apps, and announce more partnerships that should fix most, if not all, of those problems.